div#tinyKnowledgeGraph {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/tiny-knowledge-graph.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1250x750: 40% */
    width: 500px;
    height: 300px;
}

div#courseKnowledgeGraph {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/course-knowledge-graph.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1216x582: 60% */
    width: 730px;
    height: 349px;
}

div#largeKnowledgeGraph {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/large-knowledge-graph.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1600x832:  */
    width: 730px;
    height: 349px;
}

div#calculusKnowledgeGraph {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/calculus-knowledge-graph.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1600x832:  */
    width: 730px;
    height: 349px;
}

div#spacedRepetition {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/spaced-repetition.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1450x850:  */
    width: 580px;
    height: 340px;
}

div#knowledgeFrontier {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/knowledge-frontier.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1600x1600:  */
    width: 500px;
    height: 500px;
}

div#taskSelection {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/task-selection.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1920x1920:  */
    width: 500px;
    height: 500px;
}

div#explicitReview {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 0px;
    background: url('/img/explicit-review.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1920x1920:  */
    width: 400px;
    height: 400px;
}

div#implicitReviews {
    margin: 0 auto;
    margin-top: 0px;
    margin-bottom: 50px;
    background: url('/img/implicit-reviews.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1920x1920:  */
    width: 400px;
    height: 400px;
}

div#spacedReviewPacing {
    margin: 0 auto;
    margin-top: 50px;
    margin-bottom: 50px;
    background: url('/img/spaced-review-pacing.png');
    background-size: 100%;
    background-repeat: no-repeat;
    /* 1920x1920:  */
    width: 800px;
    height: 800px;
}